Kate-comeau this is for you:)

I am 26 and i recently noticed that my hair is thinning. i have always had fine hair but have noticed a difference lately. My mother nor my father are bald so i think it may be because of my diet. I eat horribly i dont drink much water and I have lots of stress. What can i start to eat to number 1 make my hair fuller but also my body as well. What kinds of supplements? also is it possible if i start now will my hair actually become fuller and stop thinning? I am very worried that I may have started something that is irreversible because i was too lazy to take care of myself. thank you for your time: )